Transmission of coupled-gap solitons in non-linear periodic media

Abstract

The theoretical interests in gap solitons have grown recently due to their unusual properties. For example, it was found that gap solitons can propagate in a Nonlinear Periodic Dielectric Medium (NPDM) with a group velocity much slower than the usual medium group velocity. The existence of stationary solitons in a NPDM was first investigated by Chen and Mills.1 Later, de Sterke-Sipe and Christodoulides-Joseph showed that it is possible to propagate moving solitons in a NPDM. In this paper, we study the propagation of two pulses with orthogonal linear polarizations in a nonlinear periodic structure with χ(3) nonlinearity. Specifically we derive the coupled nonlinear Schrödinger equations and find their solitary-wave solutions in a simple case. We show that two orthogonally polarized pulses can co-propagate as a coupled gap soliton through a nonlinear periodic structure while each pulse alone will be strongly reflected due to the Bragg reflection. Based on the results, we present a new all-optical switching scheme and investigate its operational characteristics.